Battery powered electronic devices, for example, digital cameras, portable telephones, and portable computers, often have some active circuitry that continues to receive power even when a power switch is switched off. For example, a real-time clock circuit, or keyboard activity monitoring circuitry, may continue to remain active when the rest of a device is powered off. If a device is left powered off for an extended time without recharging the batteries, the active circuitry may completely discharge the batteries. For some battery technologies, if the battery is fully discharged, the battery may leak corrosive fluids into the device being powered. For some battery technologies, the ability of the battery to be recharged is impaired if the battery is allowed to fully discharge. Accordingly, manufacturers of some battery powered electronic devices recommend that if the devices are going to be unused for an extended period of time then the batteries should be removed.
In some battery-powered electronic devices, a reset function is needed. Sometimes an electrical reset switch is provided that grounds a reset signal on a processor. In some devices, the manufacturer recommends removing the batteries to provide a power-on reset function. Some battery powered electronic devices have a capacitive energy storage device that provides power when the batteries are removed. If, for example, the device has a real-time clock, this enables the batteries to be replaced without having to reset the clock. If a power-on reset is needed, capacitor discharge time may be a substantial number of minutes. Accordingly, manufacturers of some battery powered electronic devices recommend that if a power-on reset is needed, then the batteries should be removed for an extended period of time.
Removal of batteries is an inconvenience to a customer. Battery removal may require removal of screws or covers. There is a risk of misplacing or losing batteries, screws, and covers. There is a risk of damage to covers and internal parts. There is a need for a convenient way to prevent battery discharge, and to provide a power-on reset function, without requiring physical removal of batteries.